First of all what is a graphic designer?
A graphic designer works to provide businesses with any visual communications they may require.
This includes logo design, layout design for printed items such as signage, stationery, and marketing materials (brochures, flyers and so on) for example.
In today’s Internet age a graphic designer is often also able to design electronic communications such as e-newsletters, websites and more.
Not all graphic designers cover all service areas mentioned, however a skilled and experienced graphic designer is worth their weight in gold.
Hiring a graphic designer who has a few years of experience working with business owners to create memorable visual communications has some distinct advantages over working with newer designers.
These Include to name just a few
1.

Speed & Efficiency - An experienced designer is often used to working on many different projects at once; managing their time effectively, and delivering your project to agreed timescales.
If you are hiring your designer on an hourly rate basis rather than being quoted ‘for the job’ an experienced designer quoting you a higher rate per hour might actually bill you for less at the end of the project if they are quicker than a designer quoting less per hour.
It’s always good to get an estimate from your designer as to how long they expect the task to take, or even better try and get them to quote ‘for the job’ regardless of how long it takes them. Don’t forget to ask if revisions are included in the ‘for the job’ price.
2.

Printing Pitfalls – There are several print layout design pitfalls a designer can fall into if they don’t know their trade inside out. These include;
Print Bleed: Any document laid out for print must have a few mm’s of bleed overlapping the edge of the document size (i. the designers document must be bigger than the actual printed item) – each print firm has a different requirement for how many mm’s that should be. An experienced graphic designer will understand the need to find out before they start designing, and hopefully be proactive enough to get in touch with the print firm themselves to find out.
Not offering correct dpi for images: Everyone knows that if you are offering a printing firm an image type that is made up of pixels such as TIFF or JPEG, that the image must be a minimum of 300 dpi (dots per inch)…. or do they all know this? Is your designer aware of this?
Likewise if you are offering the print firm a vector image such as EPS, or AI…. that pixels are irrelevant because scalable vector images output by professional design software, are not made up of pixels. More information about vector images at www.trulyace.

com/scalablegraphics.html
Thin Lines in Graphics: Any line used in a graphical image is made up of a ‘line point size’, this can vary from as tiny as 0.10 all the way up to 1,2,3, or even 10 point size and higher. The bigger the point size the fatter the line is and vice versa.
An inexperienced designer – perhaps one who has produced a detailed illustration with much in the way of fine details - may not realise that you must never hand any design over to a printing firm that contains a line size smaller than 0.25 – printing presses simply cannot print lines any thinner than 0.25 points.
Colours – What is a hex colour? What is a Pantone Colour? What are CMYK colours? Never mind what they are, how does one choose between each colour method available to them before their lovely designs are printed? Your designer should know this, but not all inexperienced designers fully understand the methods required for selecting print colours and this can lead to unexpected print results. More information at www.trulyace.

com/technicalinformation.html
So that just gives you a very brief overview of why experience counts in graphic design, and to ensure that your designer is sufficiently experienced to take care of the essential practical aspects of designing for your business.